Reporting terminal capabilities for supporting short message service

ABSTRACT

A method for delivering a short message service (SMS) message to an interworking wireless local area network user equipment (UE) begins by registering the UE with an Internet Protocol short message gateway (IP-SM-GW). A capability report is sent from the UE to the IP-SM-GW, the capability report including the capabilities of the UE. A SMS message is transmitted from a short message service center (SMSC) to the IP-SM-GW. The capabilities of the UE are evaluated at the IP-SM-GW to determine whether the UE can receive the SMS message, and the SMS message is delivered to the UE via the IP-SM-GW if the UE has the capabilities to receive the SMS message.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit of U.S. Provisional Application No. 60/576,700, filed Jun. 2, 2004, which is incorporated by reference as if fully set forth herein.

FIELD OF INVENTION

The present invention generally relates to wireless local area networks (WLANs), and more particularly, to a method and apparatus for reporting terminal capabilities to support short message service (SMS) over a WLAN.

BACKGROUND

The current architecture for supporting SMS over Internet Protocol (IP) on a WLAN uses a SMS proxy on behalf of the user equipment (UE) at the IP gateway. The SMS proxy acts as a terminal front end to the Signaling System No. 7 (SS7) mobile application part (MAP) (i.e., the existing SMS for global system for mobile communication (GSM)/general packet radio service (GPRS)). The control signaling associated with SMS is not currently covered by the proxy function.

SUMMARY

The present invention extracts the SMS data message from the SS7/MAP format and sends the message to an interworking WLAN (I-WLAN) UE using an IP-based protocol. In the present invention, the SMS proxy function in the SMS IP gateway performs all of the functions performed by the SMS client in a GSM/GPRS UE.

A method for delivering a short message service (SMS) message to an interworking wireless local area network user equipment (UE) begins by registering the UE with an Internet Protocol short message gateway (IP-SM-GW). A capability report is sent from the UE to the IP-SM-GW, the capability report including the capabilities of the UE. A SMS message is transmitted from a short message service center (SMSC) to the IP-SM-GW. The capabilities of the UE are evaluated at the IP-SM-GW to determine whether the UE can receive the SMS message, and the SMS message is delivered to the UE via the IP-SM-GW if the UE has the capabilities to receive the SMS message.

A method for sending a SMS message from an interworking wireless local area network user equipment (UE) begins by registering the UE with an IP-SM-GW. A capability report, including the capabilities of the UE, is sent from the UE to the IP-SM-GW, whereby the IP-SM-GW acts as a proxy for the UE. A SMS message is transmitted from the UE to the IP-SM-GW. The SMS message is sent to a SMSC via the IP-SM-GW.

A system for delivering a SMS message to an interworking wireless local area network user equipment (UE) includes a SMSC, an IP-SM-GW, and a capability report. The SMSC transmits a SMS message for delivery to the UE. The UE registers with the IP-SM-GW, the IP-SM-GW receiving the SMS message transmitted by the SMSC. The capability report, including the capabilities of the UE, is sent from the UE to the IP-SM-GW. The IP-SM-GW evaluates the capability report and delivers the SMS message to the UE if the UE has the capabilities to receive the SMS message.

A system for sending a SMS message from an interworking wireless local area network user equipment (UE) includes an IP-SM-GW, a capability report, and a SMSC. The UE registers with the IP-SM-GW and send the capability report, including the capabilities of the UE, to the IP-SM-GW. The IP-SM-GW acts as a proxy for the UE, and receives a SMS message sent by the UE. The IP-SM-GW sends the SMS message to the SMSC.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding of the invention may be had from the following description of a preferred embodiment, given by way of example, and to be understood in conjunction with the accompanying drawings, wherein:

FIG. 1 is a block diagram of a SMS system;

FIG. 2 is a flow diagram of a method for delivering a short message to a WLAN UE;

FIG. 3 is a flow diagram of a method for delivering a short message to a WLAN UE using SIP/IMS;

FIG. 4 is a flow diagram of a method for sending a short message from a WLAN UE; and

FIG. 5 is a flow diagram of a method for sending a short message from a WLAN UE using SIP/IMS.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereafter, a user equipment (UE) includes, but is not limited to, a wireless transmit/receive unit (WTRU), a mobile station, a fixed or mobile subscriber unit, a pager, or any other type of device capable of operating in a wireless environment. When referred to hereafter, a base station includes, but is not limited to, a Node B, a site controller, an access point, or any other type of interfacing device in a wireless environment. Although the following embodiments are described in conjunction with a UE, the embodiments also apply to a WTRU.

FIG. 1 is a diagram of a SMS system 100. The system 100 includes a short message entity (SME) 102 which can send or receive short messages. The SME 102 communicates with a short message service center (SMSC) 104 that is responsible for the relaying and the store-and-forwarding of a short message between the SME 102 and a UE.

A gateway mobile switching center (GMSC)/SMS interworking MSC (SMS-IWMSC) 106 has two functions: a GMSC function and a SMS-IWMSC function. The GMSC function receives a short message from the SMSC 104, interrogates a home subscriber server (HSS)/home location register (HLR) 108 for routing information, and delivers the short message to the visited MSC or the serving GPRS support node (SGSN) of the recipient UE. The SMS-IWMSC function receives a short message from a UE and submits it to the appropriate SMSC. While shown as separate entities, the SMSC 104 and the GMSC/SMS-IWMSC 106 can be integrated into a single entity.

The HSS/HLR 108 communicates with an authentication, authorization, and accounting (AAA) server 110 for the WLAN. The AAA server 110 contains information relating to which UEs can access the WLAN, what services the UEs are permitted to use, and accounting records for each UE.

In a non-IP based setting, the GMSC/SMS-IWMSC 106 communicates with a MSC 112 and a SGSN 114. The MSC 112 and the SGSN 114 both communicate with a UE 116. The MSC 112 provides functions such as switching, signaling, paging, and inter-MSC handover. The SGSN 114 performs functions such as routing and mobility management.

When routing a SMS message, the GMSC/SMS-IWMSC 106 performs a MAP request to the HSS/HLR 108 to determine the address of the MSC 112 or the SGSN 114 where the SMS message is to be routed for delivery to the UE 116.

In an IP based setting, an IP short message gateway (IP-SM-GW) 118 provides protocol interworking between the IP client and the network for delivering a short message. The IP-SM-GW 118 communicates with the GMSC/SMS-IWMSC 106 using established MAP protocols over SS7, appearing to the GMSC/SMS-IWMSC 106 as a MSC or a SGSN. The IP-SM-GW 118 accesses an IP address database 120 to associate a mobile station integrated service digital network (ISDN) number (MSIDSN) with the IP address of a WLAN UE 122. Although the IP database 120 is shown as a separate entity, it may be located in the HSS/HLR 108, in the AAA server 110, in the IP-SM-GW 118, or any other suitable location.

The IP-SM-GW 118 uses a packet data gateway (PDG) 124 to communicate with the WLAN UE 122. The IP-SM-GW 118 supports registration and authentication of the WLAN UE 122 for SMS services, and supports security associations with the WLAN UE 122. The IP-SM-GW 118 communicates with the WLAN UE 122 using IP based protocols, maintaining the format and functionality of the SMS message.

When routing a SMS message, the GMSC/SMS-IWMSC 106 performs a MAP request to the HSS/HLR 108 to determine the address of the IP-SM-GW 118. In addition, the HSS/HLR 108 provides an indication that the WLAN UE 122 is IP based (e.g., communicates with a IP-SM-GW 118 instead of a MSC 112 or a SGSN 114), provides the SS7 MAP address of the IP-SM-GW 118, and contains the necessary logic to determine that the WLAN UE 122 is connected via IP and return the address of the IP-SM-GW 118 instead of an address for a MSC or a SGSN. The AAA server 110 maintains the attach status of the WLAN UE 122, as to whether the WLAN UE 122 is IP attached.

Delivering Short Messages to a WLAN UE

A method 200 for delivering short messages to a WLAN UE is shown in FIG. 2. A tunnel between the WLAN UE 122 and the home PDG 124 is established (step 202). Following establishment of the tunnel, the UE 122 registers with the IP-SM-GW 118, establishing any necessary security association, authenticates for support of SMS services, and registers the association between the UE's MSISDN (E.164) and its IP address (step 204).

The UE 122 sends its capabilities (as a capability report) to the IP-SM-GW 118 (step 206). The UE capabilities include, for example, memory size, terminal type, screen size, and whether the UE supports session initiation protocol (SIP). The IP-SM-GW 118 uses the UE's capabilities to determine whether to reject delivery of a SMS message and to ensure that only SMS data and notifications are transmitted over IP to the UE 122.

The SMSC 104 forwards a SMS message to the SMS-GMSC 106 (step 208). The SMS-GMSC 106 interrogates the HSS/HLR 108 to retrieve routing information for the UE 122 (step 210). When a user is registered on a WLAN for delivery of SMS messages, the HSS/HLR 108 returns the address of the IP-SM-GW 118 (rather than the address of the appropriate MSC or SGSN), whereby the IP-SM-GW 118 acts as a proxy for the UE 122 (step 212). The SMS proxy (i.e., the IP-SM-GW 118) is able to reject the delivery of SMS messages based on the capabilities of the UE 122 (e.g., memory size, screen size, or terminal type) and the nature of the SMS data (text, animation, etc.).

The SMS-GMSC 106 delivers the SMS message to the IP-SM-GW 118 using protocols as if it was a SMS message delivered to a MSC or SGSN (step 214). Optionally, the IP-SM-GW 118 interrogates the database 120 to identify the IP address and relevant security parameters associated with the UE 122 (step 216).

SMS messages can be delivered by two methods: notification and direct delivery. When the notification delivery method is used, the IP-SM-GW 118 sends a SMS notification request to the UE 122 to inform it that a SMS message is available for delivery (step 218). On receipt of the SMS notification message, the UE 122 responds to the IP-SM-GW 118 with a notification acknowledgement indicating whether it wishes to receive the SMS message (step 220).

If the direct delivery method is used (steps 218 and 220 are skipped), or if a positive acknowledgement is received from the UE 122 in response to the SMS notification request, the IP-SM-GW 118 delivers the SMS message to the UE 122 using one of several possible protocols, e.g., wireless application protocol (WAP), short message peer to peer protocol (SMPP), mobile message access protocol (MMAP), extensible markup language (XML), or SIP (e.g., an IP multimedia subsystem (IMS) client) (step 222). If the IP-SM-GW 118 rejects delivery of the SMS message, then steps 216-222 are skipped, and the method 200 continues with step 224.

The IP-SM-GW 118 sends a delivery report back to the SMS-GMSC 106 (step 224). The delivery report either confirms that the SMS message was delivered to the UE 122 or informs the SMS-GMSC 106 that the SMS message could not be delivered and a reason for the failure. The SMS-GMSC 106 sends a SM delivery report status to the HSS/HLR 108 (step 226). The SMS-GMSC 106 sends the SM delivery report to the SMSC 104 (step 228). Error handling is preferably performed using the mechanisms defined in 3GPP Technical Specification (TS) 23.040v6.3.0 (2004-03), with the IP-SM-GW 118 acting as a front end for the UE 122, although other error handling techniques may be used.

FIG. 3 is a flow diagram of a method 300 for delivering a short message to a WLAN UE 122 using SIP/IMS. The UE 122 registers with a serving call session control function (S-CSCF) 302 according to the IMS registration procedure (step 310). The registration information is also stored in the HSS/HLR 108. The UE 122 sends a capability report to the IP-SM-GW 118 (step 312). The UE capabilities include, for example, memory size, terminal type, screen size, and whether the UE supports session initiation protocol (SIP). The IP-SM-GW 118 uses the UE's capabilities to determine whether to reject delivery of a SMS message, by acting as a proxy for the UE 122.

The SMSC 104 forwards a SMS message to the SMS-GMSC 106 (step 314). The SMS-GMSC 106 interrogates the HSS/HLR 108 to retrieve routing information (step 316). When a user is IMS registered, the HSS/HLR 108 returns the address of the IP-SM-GW 118 along with the address of the MSC.

The SMS-GMSC 106 delivers the SMS message to the IP-SM-GW 118, in the same manner that it delivers a SMS message to an MSC or a SGSN, carrying the MSISDN of the target UE 122 (step 318). The IP-SM-GW 118 uses the TEL-URL of the target UE 122 to populate a SIP Request URI, and then sends the SMS message to the S-CSCF 302 using the SIP MESSAGE method (step 320). The S-CSCF 302 then forwards the SIP MESSAGE (SMS message) to the UE 122 (step 322).

Upon receipt of the SIP MESSAGE (SMS message), the UE 122 responds by sending a 200 OK message to the S-CSCF 302 (step 324). It is noted that the 200 OK message is not a delivery report, as a 200 OK message cannot carry the information contained in a delivery report. The S-CSCF 302 sends a 200 OK message to the IP-SM-GW (step 326).

The UE 122 then sends a delivery report to the S-CSCF 302 using the SIP MESSAGE method (step 328). Based on filter information, the S-CSCF 302 forwards the SIP MESSAGE (delivery report) to the IP-SM-GW 118 (step 330), which extracts the delivery report from the SIP MESSAGE format and sends the delivery report to the SMS-GMSC 106 (step 332).

The SMS-GMSC 106 sends a SM delivery report status message to the HSS/HLR 108 (step 334). The SMS-GMSC 106 forwards the delivery report to the SMSC 104 (step 336). The IP-SM-GW 118 acknowledges that the delivery report was sent to the SMSC 104 by sending a 200 OK message to the S-CSCF 302 (step 338). The S-CSCF acknowledges the delivery report to the UE 122 by sending a 200 OK message to the UE (step 340).

Sending Short Messages from a WLAN UE

FIG. 4 is a diagram of a method 400 for sending a short message from the WLAN UE 122. A tunnel between the UE 122 and the home PDG 124 is established (step 402). Following establishment of the tunnel, the UE 122 registers with the IP-SM-GW 118 establishing any necessary security association, authenticates for support of SMS services, and registers the association between the UE's MSISDN (E.164) and its IP address (step 404). The association information for the UE 122 is also recorded in the HSS/HLR 108. The UE 122 sends its capability information to the IP-SM-GW 118 to enable the SMS terminal proxy operation (step 406). After sending the capability information, the IP-SM-GW 118 handles all SMS control messages for the UE 122 (step 408).

The UE 122 delivers a SMS message to the IP-SM-GW 118, using e.g., WAP, SMPP, MMPP, or XML (step 410). The IP-SM-GW 118 extracts the SMS message and forwards it to the SMS-IWMSC 108 using the standard MAP, as if the IP-SM-GW 118 was a MSC or a SGSN (step 412).

The SMS-IWMSC 106 forwards the SMS message to the SMSC 104 (step 414). Upon receipt of the SMS message, the SMSC 104 sends a delivery report to the SMS-IWMSC 106 (step 416). The SMS-IWMSC 106 sends the delivery report to the IM-SM-GW 118 (step 418). The delivery report is sent with an indication of whether the delivery was a success or a failure. If there was a delivery failure, the SMSC 104 reports back to the SMS-IWMSC 106 and the SMS-IWMSC 106 will attempt to retransmit the SMS message. If the number of retries exceeds a threshold, then a delivery failure report will be sent to the UE 122.

The IP-SM-GW 118 sends the delivery report to the UE 122 using a proprietary mechanism and/or protocols (step 420). In a preferred embodiment, the delivery report is sent via an IP-based transfer, such as SMPP. The delivery report either confirms that the SMS message was delivered to the SMSC 104 or informs the UE 122 that the SMS message could not be delivered and a reason for the failure.

As with message receipt, the error handling for message sending is preferably performed using the mechanisms defined in TS 23.040 v6.3.0 (2004-03), with the IP-SM-GW 118 acting as a front end for the UE 122, although other error handling techniques may be used.

The implementation of new procedures in the I-WLAN UE side is reduced, where only simple operations are performed to confirm reception of the SMS data or to report a corrupt message for retransmission purposes.

FIG. 5 is a flow diagram of a method 500 for sending a short message from a WLAN UE 122 using SIP/IMS. The UE 122 registers with a S-CSCF 502 according to the IMS registration procedure (step 510). The registration information is also stored in the HSS/HLR 108. The UE 122 sends a capability report to the IP-SM-GW 118 (step 512). The UE capabilities include, for example, memory size, terminal type, screen size, and whether the UE supports session initiation protocol (SIP). The IP-SM-GW 118 uses the UE's capabilities to enable SMS terminal proxy operation, allowing the IP-SM-GW 118 to handle all SMS control messages for the UE 122.

The UE 122 submits a SMS message to the S-CSCF 502 using the SIP MESSAGE method (step 514). The S-CSCF 502 forwards the SIP MESSAGE (SMS message) to the IP-SM-GW 118 based on filter information (step 516). The IP-SM-GW 118 indicates that the SIP MESSAGE (SMS message) was received by sending a SIP 202 Accepted message to the S-CSCF 502 (step 518). The message receipt information is forwarded by the S-CSCF 502 to the UE 122 by a SIP 202 Accepted message (step 520).

The IP-SM-GW 118 extracts the SMS message from the SIP MESSAGE and forwards it to the SMS-IWMSC 106 using standard MAP signaling (step 522). The address of the SMSC 104 is extracted either from the R-URI of the SIP MESSAGE or from the SMS content. The SMS-IWMSC 106 forwards the SMS message to the SMSC 104 (step 524).

The SMSC 104 sends a submit report to the SMS-IWMSC 106 (step 526). The submit report is an acknowledgement that the SMS message was received by the SMSC 104. The SMS-IWMSC 106 sends the submit report to the IP-SM-GW 118 (step 528). The IP-SM-GW 118 sends the submit report to the S-CSCF 502 using the SIP MESSAGE method (step 530). The S-CSCF 502 forwards the SIP MESSAGE (submit report) to the UE 122 (step 532). The UE 122 acknowledges receipt of the SIP MESSAGE (submit report) by sending a 200 OK message to the S-CSCF 502 (step 534), which is then forwarded to the IP-SM-GW 118 (step 536).

Although the features and elements of the present invention are described in the preferred embodiments in particular combinations, each feature or element can be used alone (without the other features and elements of the preferred embodiments) or in various combinations with or without other features and elements of the present invention. 

1. A method for receiving a short message service (SMS) message by user equipment (UE), comprising: registering with a serving call state control function (S-CSCF) in a network using an Internet Protocol Multimedia Subsystem (IMS) registration procedure; sending capability information to the network, the capability information indicating SMS message capabilities of the UE; and in response to sending the capability information, receiving the SMS message using Session Initiation Protocol (SIP) via a Internet Protocol short message gateway (IP-SM-GW) and the S-CSCF.
 2. The method according to claim 1, wherein the capability information includes at least one of: available memory size, terminal type, screen size, and SIP support.
 3. The method according to claim 1, further comprising: in response to receiving the SMS message, communicating a delivery report to the network using SIP.
 4. A method for sending a short message service (SMS) message from a user equipment (UE), comprising: registering with a serving call state control function (S-CSCF) in a network using an Internet Protocol Multimedia Subsystem (IMS) registration procedure; sending capability information to the network, the capability information indicating SMS message capabilities of the UE; and transmitting the SMS message using Session Initiation Protocol (SIP) to a short message service center (SMSC) via the S-CSCF and a Internet Protocol short message gateway (IP-SM-GW).
 5. The method according to claim 4, wherein the capability information includes at least one of: available memory size, terminal type, screen size, and SIP support.
 6. The method according to claim 4, further comprising: receiving a delivery report from the SMSC.
 7. The method according to claim 6, wherein the delivery report indicates whether the SMS message was delivered to the SMSC.
 8. The method according to claim 7, wherein if the delivery report indicates that the SMS message was not delivered to the SMSC, then the delivery report also indicates a reason for delivery failure.
 9. A user equipment (UE) comprising: a registering device configured to register the UE with a serving call state control function (S-CSCF) in a network using an Internet Protocol Multimedia Subsystem (IMS) registration procedure; a transmitter configured to send capability information to the network, the capability information indicating short message service (SMS) capabilities of the UE; and a receiver configured to receive the SMS message using Session Initiation Protocol (SIP) via the S-CSCF and the a Internet Protocol short message gateway (IP-SM-GW).
 10. The UE according to claim 9, wherein the capability information includes at least one of: available memory size, terminal type, screen size, and SIP support.
 11. A user equipment (UE) comprising: a registering device configured to register the UE with a serving call state control function (S-CSCF) in a network using an Internet Protocol Multimedia Subsystem (IMS) registration procedure; and a transmitter configured to: send capability information to the network, the capability information indicating short message service (SMS) capabilities of the UE; and send a SMS message using Session Initiation Protocol (SIP) to a short message service center (SM-SC) via the S-CSCF and a Internet Protocol short message gateway (IP-SM-GW).
 12. The UE according to claim 11, wherein the capability information includes at least one of: available memory size, terminal type, screen size, and SIP support.
 13. A method for delivering a short message service (SMS) message from an Internet Protocol short message gateway (IP-SM-GW) to a user equipment (UE), comprising: receiving capability information from the UE, the capability information indicating SMS message capabilities of the UE; evaluating the capability information to determine whether the UE can receive the SMS message; and delivering the SMS message to the UE using Session Initiation Protocol (SIP) via a call state control function (S-CSCF).
 14. The method according to claim 13, wherein the capability information includes at least one of: available memory size, terminal type, screen size, and SIP support.
 15. The method according to claim 13, wherein the SMS message is received from a short message service center (SM-SC).
 16. The method according to claim 13, further comprising: receiving a delivery report from the UE using SIP; and sending the delivery report to a short message service center (SM-SC).
 17. The method according to claim 16, wherein the delivery report indicates whether the SMS message was delivered to the UE.
 18. The method according to claim 17, wherein if the delivery report indicates that the SMS message was not delivered to the UE, then the delivery report also indicates a reason for delivery failure.
 19. An Internet Protocol short message gateway (IP-SM-GW), the IP-SM-GW comprising: a communications interface configured: to receive capability information from the UE, the capability information indicating short message service (SMS) capabilities of the UE; to receive an SMS message; and on a condition that the capability information indicates that the UE is capable of receiving the SMS message, to deliver the SMS message to the UE using Session Initiation Protocol (SIP) via a serving call state control function (S-CSCF).
 20. The IP-SM-GW according to claim 19, wherein the capability information includes at least one of: available memory size, terminal type, screen size, and SIP support.
 21. The IP-SM-GW according to claim 19, wherein the communications interface is configured to receive the SMS message from a short message service center (SM-SC).
 22. The IP-SM-GW according to claim 19, wherein the communications interface is further configured: to receive a delivery report from the UE using SIP; and to send the delivery report to a short message service center (SM-SC).
 23. The IP-SM-GW according to claim 22, wherein the delivery report indicates whether the SMS message was delivered to the UE.
 24. The IP-SM-GW according to claim 23, wherein the delivery report indicates that the SMS message was not delivered to the UE and indicates a reason for delivery failure.
 25. A method for use in a network node, the method comprising: receiving Internet Protocol Multimedia Subsystem (IMS) registration data from the UE for registering the UE with a serving call state control function (S-CSCF) according to an IMS registration procedure; transmitting the IMS registration data to the S-CSCF; receiving capability information from the UE, the capability information indicating short message service (SMS) capabilities of the UE; transmitting the capability information of the UE; receiving a Session Initiation Protocol (SIP) message via the S-CSCF and a Internet Protocol short message gateway (IP-SM-GW), wherein the SIP message includes SMS content; and transmitting the SIP message to the UE.
 26. The method of claim 25 wherein the network node is a packet data gateway (PDG).
 27. A network node comprising: a communications interface, configured to: receive Internet Protocol Multimedia Subsystem (IMS) registration data from the UE for registering the UE with a serving call state control function (S-CSCF) according to an IMS registration procedure; transmit the IMS registration data to the S-CSCF; receive capability information from the UE, the capability information indicating short message service capabilities of the UE; transmit the capability information of the UE; receive a Session Initiation Protocol (SIP) message via the S-CSCF and a Internet Protocol short message gateway (IP-SM-GW), wherein the SIP message includes short message service (SMS) content;and transmit the SIP message to the UE.
 28. The network node of claim 27 wherein the network node is configured to implement packet data gateway (PDG) functionality.
 29. A method for use in a network node, the method comprising: receiving Internet Protocol Multimedia Subsystem (IMS) registration data from the UE for registering the UE with a serving call state control function (S- CSCF) according to an IMS registration procedure; transmitting the IMS registration data to the S-CSCF; receiving capability information from the UE, the capability information indicating short message service (SMS) capabilities of the UE; transmitting the capability information of the UE; receiving a Session Initiation Protocol (SIP) message from the UE, wherein the SIP message includes SMS content; and transmitting the SMS content to a short message service center (SM-SC) via the S-CSCF and a Internet Protocol short message gateway (IP-SM-GW).
 30. The method of claim 29 wherein the network node is a packet data gateway (PDG).
 31. A network node comprising: a communications interface configured to: receive Internet Protocol Multimedia Subsystem (IMS) registration data from the UE for registering the UE with a serving call state control function (S-CSCF) according to an IMS registration procedure; transmit the IMS registration data to the S-CSCF; receive capability information from the UE, the capability information indicating short message service (SMS) capabilities of the UE; transmit the capability information of the UE; receive a Session Initiation Protocol (SIP) message from the UE, wherein the SIP message includes SMS content; and transmit the SMS content to a short message service center (SM-SC) via the S-CSCF and a Internet Protocol short message gateway (IP-SM-GW).
 32. The network node of claim 31 wherein the network node is configured to implement packet data gateway (PDG) functionality. 